The proposed research seeks to clarify the contribution of temporal and associative relations in the acquisition of auto-shaped key-pecking by pigeons. Preliminary results indicate that the rate of acquisition of a conditioned key-peck in a trial-by-trial paradigm depends upon (1) the intertrial interval (ITI) between signalled food presentations, and (2) the presence of additional signals cuing the absence of food. Acquisition is facilitated by long time periods between positive trials, and retarded by the introduction of unreinforced trials between reinforced trials. The proposed research seeks to account for these relationships by studying the following interrelated questions: 1. To what extent can the ITI functions we obtained be attributed to an associative factor based upon increases in informativeness of the trial signal as the intertrial interval is lengthened? 2. To what extent is the absolute as opposed to the relative duration of the intertrial interval a determinant of the number of trials needed to acquire an autoshaped response? 3. To what extent is the acquisition of an auto-shaped key-peck influenced by any of the following three factors? a. visual intensity (e.g., ITI dark vs. ITI lit) b. density of signal onsets for the unrewarded signal. The proposed experiment should provide fundamental information concerning the role of information and temporal parameters in conditioning and in evaluating the "classical" and the "instrumental" contributions to the auto-shaped key-peck.